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That One Boss / World of Warcraft

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"It would be unfair to make you fight all four Advisors at once, but...fair treatment was never shown to my people. I'm just returning the favor."
Kael'thas Sunstrider
He's got a giant hammer and he's literally on fire! What are we gonna do?

This page is about bosses in World of Warcraft that give away grief like it's candy. We need no advice for defeating these monstrosities- that defeats the purpose!

REMINDER: Hard modes, being optional, count as Bonus Bosses.


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    Classic World of Warcraft 
  • Arugal, the last boss of Shadowfang Keep, can immobilize your party then teleport away to attack them with Shadow Bolts, and can also turn one party member into a werewolf that attacks the others, making him exceptionally difficult for his level and considerably different from other bosses.
  • Renault Mograine in Scarlet Monastery Cathedral is capable of summoning any trash that has not already been cleared, meaning that he is easily capable of wiping the group if any player decides to attack him before doing so. And to make matters worse, he is part of a 2-stage encounter, as after he is slain, High Inquisitor Whitemane shows up and brings him back from the dead once she starts running low on health.
  • Archaedas, end boss of Uldaman, is a major step up in terms of complexity from anything previously encountered by players while leveling because of large numbers of adds that swarm the other players and heal the boss. There's also the fact that he was level 47 while the dungeon could be entered as early as level 38. The difficulty curve was tweaked in a later patch.
  • Majordomo Executus was considered a massively difficult encounter due to the need to coordinate the simultaneous tanking and crowd control of nine separate mobs — this in addition to the harsh requirements to summon him in the first place.
  • Onyxia was pretty infamous back in the day, notably for her roar ability, which sent players running in fear, which would be bad enough of its own. Making it worse is the fact that the arena had some caves full of eggs ready to hatch into dragon whelps, and it was not unknown for players to uncontrollably run into them due to her fear spell, bringing the wrath of several dozen whelps upon the raid. Her Deep Breath was also pretty infamous, with entire raids getting wiped due to positioning mistakes or because Onyxia just felt like it that particular day (there is a video online of a buggy Onyxia obliterating a raid with 7 Deep Breaths in quick succession).
  • Razorgore, the first boss of Blackwing Lair, requires tanks to pick up and kite potentially dozens of adds before the boss can even be fought, while healers do everything in their power not to attract attention. Many Molten Core/Onyxia level guilds simply folded on this fight.
    • At higher levels, a new element of difficulty comes into play; it's possible for people who don't know the fight to kill him (which is fairly easy, as he has less than 500,000 HP) before destroying the eggs, which results in him wiping the raid.
  • Immediately after Razorgore comes Vaelastrasz, an absolute balls-to-the-wall slugfest on a short timer where one mistake with aggro can wipe the raid. Vael was renowned as a guild killer back in the day. Keep in mind that Razorgore and Vaelastrasz were not simply the first two bosses in Blackwing Lair—they were the first two encounters, as well as the two hardest bosses in the instance (only Nefarian himself comes close)! This is a textbook example of how not to build a dungeon, because while Blackwing Lair was very impressive, most players never got a chance to see it because of Razorgore and Vael.
    • The boss also has a guaranteed death mechanic that is independent of gear or level. At level 90 a solo player will be able to kill the boss effortlessly, but are unlikely to do so before he applies his irremovable debuff that will reduce their maximum health until it reaches zero. Classes with pets might get lucky and have him kill the pet instead, but otherwise someone is going to die no matter what.
  • Another boss is Broodlord Lashlayer: If your tanks weren't in essentially the very best gear possible, they would probably die to Mortal Strike because it could crit for 8k on plate. You'd likely need multiple tanks with great gear because Broodlord uses a knockback that reduces the target's total threat by 50%. If you're melee and you ripped aggro, prepare to die. If you're ranged and you ripped aggro, you better run in and die fast otherwise Broodlord will cleave and kill your ranged/healers. Then if you wipe, have fun reclearing the Suppression Room; easily some of the worst trash in the whole game.
    • And the Suppression Field reduces your movement to 1/4 of normal and your attack and casting speed to 1/5 of normal. Walking through is a chore and fighting is extraordinarily difficult.
  • Ayamiss the Hunter deserves special mention due to the tendency of players not familiar with the fight to accidentally aggro him before the room was cleared of trash or the raid prepared.
  • Dr. Weavil. If you wanted a chance at getting the Black Qiraji Battle Tank, you needed to fight him. He employed a permanent mind control, and a powerful multi-target nuke with a 2 second stun. You needed at least 10 people to fight him, and those 10 people would also be trying to ring that gong at the end first.. The whole chain was full of these. Maws, Lord Lakmaeran (Who only one person could loot) and his many chimeraoks.. It was worth it in the end, though. The mount is pretty awesome.
    • You can fight him but you can't get the Black Qiraji mount anymore, removing virtually all the incentive to kill him.
  • Viscidus in the Temple of Ahn'Qiraj has a special mechanic that requires him to be frozen with ice magic and shattered before he can be defeated. Unfortunately, this means that many raids on him, which may not have a Frost Mage or Death Knight, or the ones that do not have enough frost magic cannot possibly defeat him.
    • Death knights are indeed excellent for this fight, although since they were not introduced until two expansions later this was of little comfort to original raiders. Years later a Mists of Pandaria patch added a unique pet that could be dropped by the boss, but anyone other than death knights will still find it impossible or at least very difficult to beat solo.
    • Note that a further patch reduced the necessary number of frozen stacks and physical attacks necessary; additionally, the Elemental Force weapon enchant on a spare weapon is a cheap way to proc the frost effect, as Elemental damage type includes the Frost school.
  • Princess Huhuran is a gear-check boss, requiring insane levels of Nature resistance and near-perfect timing. Any less and you might as well not even attempt her.
  • Immediately after Huhuran in Ahn'Qiraj comes the Twin Emperors, a sheer coordination and teamwork fight that can still frustrate players two expansions later, due to the fact that without precise tanking they simply heal each other to full within seconds.
    • Even four expansions later, with a character 40 levels higher than the encounter was designed for, it can still be impossible to beat this boss solo. Most classes can ignore the original healing mechanics by damaging one of the bosses faster than they can regenerate, although it can still be a pretty close thing. However, since one boss is immune to all magic damage and the other is immune to all physical damage this will not work for classes whose attacks are a hybrid of the two. Death Knights and Paladins use a mix of physical and magical abilities and with either boss ignoring half of their attacks they are unlikely to cause a scratch. Of course these bosses were given another desirable pet.
  • C'thun was brutally hard in his initial version, mainly due to the fact that he would cast his raid-wiping Eye Beam attack without any delay for players to enter the room. He was actually so difficult that players came to the conclusion that the fight was literally impossible to win; unbeatable at the current level of gear. Whether this was true or not, Blizzard eventually nerfed the encounter and the first kills came hours later. However, even at 80, if someone jumps the gun, the raid will likely wipe if he does Eye Beam.
    • C'Thun remains the only raid boss to be completely un-beaten prior to any sort of nerf (legitimately at least: one guild did kill him, but it was by using an exploit that allowed them to basically walk through the walls in the room).
  • Old Naxxramas deserves its title as the final and most difficult raid dungeon of classic WoW. It would be easier to list the bosses that are not That One Boss, but some standouts are listed below.
    • Patchwerk is a gear check boss that requires perfect timing from the healers to avoid having the tanks die.
    • Gothik the Harvester is easy once you get to fight him. The trouble is the dozens of creatures he summons to attack you first.
    • Anub'Rekhan would summon adds from dead players in addition to the dead adds. Cue exponential hell.
    • Thaddius is pretty bad for groups that can't figure out how to move properly on his Polarity Shift, especially since each death makes it significantly harder to beat his berserk timer. Not to mention the mental defectives who need Slow Fall every time just to make that damn jump from the minibosses' platform to Thaddius.
    • Heigan the Unclean has a unique mechanic requiring players to move across a floor in sync, chasing the "safe spot" amid lethal eruptions. The so-called "Heigan Dance" claims far more lives than the boss himself, who is notably easy. In particular, it's extremely sensitive to the latency of your connection to the game, meaning players who disconnect or lag behind others are pretty much doomed. Even the most hardcore guilds out there wouldn't yell at you for dying during Heigan the Unclean. (Heck, they won't even yell at you now, when there's an achievement for completing Naxxramas without anyone dying...and another for defeating Heigan without anyone dying!) if you lag. It used to be a slogan that lag was a very passable reason for dying against Heigan...heck, you can even lag a tad and die! Another thing that made Heigan bad was that in order to see the particles, you had to turn the graphics settings up. Not a good idea for some people; given that part of the draw of the game is that you can run it on a toaster. In addition to server and clientside lag, you could lag running the particles.
    • The Four Horsemen had the strictest timing and movement requirements of any boss before or since, needing as many as eight tanks to perform correctly. The few guilds that successfully defeated this encounter had no trouble at all with the remaining bosses, and was widely considered the hardest boss(es) to kill until the instance was retuned. They still are an incredibly complex positioning affair, and PUGs tend to not understand where to tank them or how to switch off, thus resulting in people getting two marks at once or being AoEd to death because no one's close enough to the two in the back The whole thing was made worse by the fact that the tanks had to have their taunts land on every single "rotation". And that taunt relied on "Spell hit". It was not uncommon for high end guild to "pinch" tanks with 4 pieces of Tier 3 gear (which improved the chance for a taunt to land) from other high end guilds, causing a fair bit of friction within the community, as this was before you could pay to transfer your character to a different realm.
    • If you don't consider The Four Horsemen to be the most difficult boss, it's probably because you think it is Sapphiron. It is widely considered harder than even the final boss. The fight was difficult because it had many mechanics which combined to make positioning very difficult. Melee would have to clump around one of the two hind legs to avoid the usual frontal cleave and tail swipe common to most dragons, and the entire room was being swathed with large, mobile, and very deadly blizzards that could come close enough to the melee clump to demand that they all leave immediately and get no damage on the boss. Not only did the blizzards do very high damage and slow you heavily, but the visual effect made it sometimes difficult to perceive exactly where the area-of-effect ended and began. The final constraint upon positioning was Frost Breath, an attack that would instantly kill you unless you broke line-of-sight with the boss by hiding behind 5 random players who are turned into Ice Blocks prior. Keep in mind all these positioning demands were for a 40 man raid group, not a 10/25 one. Finally, Frost Aura consistently damaged all 40 members of your raid. This served to really tax healers and made heal-bombing those unlucky enough to get caught in a Blizzard that much more difficult.
    • Gluth can devour his adds, which heals him and makes victory impossible for those who don't know how to kill them.
    • Frogger isn't exactly a boss, but enough players have died trying to avoid the moving slimes that it has become somewhat notorious. It has gotten to the point where people are so tired of people dying to Frogger during the walk back to Those Three Bosses after it (seriously, Grobbulus, Gluth and Thaddius are all after it, all guaranteeing lots of wipes) that they simply have someone ankh and resurrect everyone individually...

    The Burning Crusade 
  • Warbringer O'mrogg in Shattered Halls is a two-headed ogre that occasionally chooses to attack a random player other than the tank, and can't be taunted. Bring a bunch of cloth-wearers in there and prepare to get squished.
  • Blackheart the Inciter in Shadow Labyrinth was another pure joy to fight. He would mind control the whole party at regular intervals and force you to kill one another. He'd also make you burn your major cooldowns on one another so you didn't have them to fight him with, including the ones that could potentially kill you once you resumed control of your character—like making a paladin healer use Lay On Hands, a spell that heals for the paladin's maximum health at the cost of all their mana, leaving them unable to heal the party.
  • Kael'thas Sunstrider, in Magister's Terrace. Sure he is a Degraded Boss from his former status as the Final Boss of Tempest Keep, but is still the hardest 5 man boss in Burning Crusade, due to the massive magical damage he inflicts.
  • The Shade of Aran is an atypical boss in that he has no physical attacks by default, but casts devastating spells on random targets. This turns the fight into a movement and healing struggle that becomes absurdly more difficult when he summons elementals to protect him at 40% health. While all of his spells could be interrupted, locking out all three of his magic schools (Frost, Fire, Arcane) caused him to whip out his staff and unleash a devestatingly powerful melee attack (at the time around 10k, enough to one-shot almost anyone it hit). Also, I will not move when flame wreath is cast, or the raid blows up!
  • Netherspite (technically a Bonus Boss, although this could be said of at least half the bosses in Karazhan), is of the "one stupid mistake can wipe the raid" variety. His mechanics require rotating players through a series of beams, a mistake with any one of which can result in the wrong person tanking or taking damage and completely wreck the plan.
  • The Chess event, the second-to-last boss in Karazhan, is a vehicle fight, where players control pieces in a game against the ghost of Medivh, who controls all his pieces simultaneously. The fight is not hard, but being a vehicle fight, the Sudden Gameplay Change can throw raids off their game. Also, the chess pieces don't scale with the players, so a raid of Mists players cannot blow their way through the event like they can every other boss, and the encounter becomes more difficult with fewer players, let alone soloing it. This encounter had several Nerfs since Mists of Pandaria dropped so that players could solo it while hunting for rare pets.
  • Lady Vashj in Serpentshrine Cavern is not especially difficult in her first and third phases, but her second phase requires players to kill Tainted Elementals that stay in one place at the edge of the arena and only appear for 15 seconds before despawning, take the Tainted Cores (which prevent the holder from moving), and throw them from raid member to raid member until someone can use them on one of her four shield generators. To make matters worse, Mooks are coming in; the Enchanted elementals allow Vashj to AoE the raid if they reach her, and the striders Fear anyone who gets close. If your group isn't coordinated, you have no chance of making it through this phase.
  • Kael'thas Sunstrider in Tempest Keep is a five phase boss that can last upwards of fifteen minutes. Assuming you survive his advisors, each of which is a miniboss in its own right, you then have to deal with his attacks, including Mind Control, a Pyroblast that will instantly kill anyone it hits, and a phase where everyone is flung up into the air and must "swim" to avoid deadly floating orbs.
  • Teron Gorefiend was of roughly average difficulty for the Black Temple when it was new, when level 70 was the maximum and people went into the Black Temple expecting a challenging raid. However, go in there at 80 and he becomes That One Boss. The Black Temple was designed for 25 players of level 70, but at level 80 everyone has much higher values in every stat, so a group of even 10 or 12 level 80s can steamroll through the place as long as at least a couple people know what they're doing. Teron Gorefiend, however, requires using new temporary abilities quickly, so if people go into Gorefiend's room without knowing the plan, they will wipe.
    • Of course, it's possible to bypass the ghost phase entirely with enough DPS (roughly 42,000; difficult for early Lich King raids but easy for Cataclysm raids).
  • Reliquary of Souls is done in three phases, each of which has completely different mechanics. In one phase, you can't heal; in the next, you can't regenerate mana, and in the third, all damage you inflict is reflected back onto yourself. Even for 85s running Black Temple for transmogrification purposes, you NEED constant interrupts in the second phase, otherwise you WILL find yourself in great peril.
  • Illidari Council is the one that gives PUGs the most trouble at level 80. Its rare that a group survives to council with more than 10 members, then there's invariably no mage (still incredibly handy for tanking purposes), a tank runs in without checking with the group, there's no caster interrupt with a short cooldown and the person assigned to interrupting instagibs themselves on reflective shield because they get bored. Definitely still requires coordination.
    • Groups with 80s can typically get past the other bosses (and possibly even Illidan himself) with 15-20 people, but they will ultimately need 25 to DPS the Council down and interrupt all the heals.
  • Kalecgos, the first boss of Sunwell Plateau, is nearly impossible for PUGs to get past. He's nearly as long as the platform is wide, and the players can aggro him if they get too close to him (sometimes if they aren't even standing on the platform). This wouldn't be as much of a problem if he didn't lock everyone who isn't on the platform out of the arena within seconds of being engaged. The fight requires killing Sarthrovarr and then bringing him down to 1% at around the same time; if you bring Kalecgos down too quickly, you lose because he stops creating portals to enable you to attack Sarthrovarr, and if you bring Sarthrovarr down too quickly, Kalecgos enrages. This becomes even more difficult if members don't take the portals to attack Sarthrovarr (which also can result in the humanoid "Kalec" dying and you losing) or don't stop DPS on Kalecgos.
  • Brutallus, the second boss, was a gear check with a very strict enrage timer, and gained a reputation, in the words of one video guide maker, as "the cock block of Sunwell".
  • Felmyst, who's only the third boss out of six at Sunwell Plateau, has a gas attack that can mind control raid members, and remains very difficult even for raids with level 80 players. Some players refuse to join Sunwell Plateau raids if they have not gotten past Felmyst.
  • M'uru was as far as many, many raids ever got, being an extremely difficult DPS race at the time. That boss ate entire guilds whole. And he wasn't even the final boss. Unlike some of the above bosses, though, M'uru did not scale as well against level 80 players as some of his peers. This has something to do with the fact that a) he has low HP in comparison and b) level 80s are very good at burning things down. Both make him considerably easier, since much of the difficulty lay in getting out the DPS to kill him in time; if you're able to kill the adds quickly or ignore them, he has less than 2 million health per form, making him quite easy to down quickly.

    Wrath of the Lich King 
  • Drakuru at the end of his quest chain in Zul'Drak. You have to control a Berserker to attack him while avoiding the barrels of blight he throws at you, and switch control immediately if you lose your Berserker. Not only is it difficult for those who don't use pets, but your character is actually a liability in the fight.
  • Ley-Guardian Eregos, in Oculus, is a unique fight conducted while mounted on drakes, using their abilities instead of your own. Once the mechanics are understood, it's simple, but try getting a pick-up group to learn it. Tellingly, it was nerfed three times.
  • Loken, in the Halls of Lightning, was at one point statistically the deadliest boss in the game, accounting for more player deaths than any other. The fact that one of his attacks forces to you remain as close to him as possible, while another requires you run away as fast as possible to avoid instant sparkly death, may account for this. He didn't last very long, however, as better gear made his dreaded Lightning Nova survivable. With good enough gear to remove the threat of being killed instantly, the fight became so easy that a single character could beat this five man encounter at the appropriate level.
  • Compared to the other Keepers in Ulduar, Mimiron is a fairly difficult fight - it's long, has four phases each possessing a number of abilities that one-shot raiders, and has a tight enrage timer. In heroic mode, it's the same with higher damage, a five-minutes-shorter enrage timer - oh, and the room is on fire.
  • Yogg-Saron in Ulduar. If you touch a roaming cloud in Phase 1, you'll spawn an add. Do this enough, and even Kingslayer groups will wipe. Once the fight begins, every player gains a new debuff called "Sanity" that starts at 100%. During the fight, specific abilities will decrease your Sanity; if Sanity reaches zero, you become Insane—Yogg-Saron controls your mind and you begin killing the raid. Yogg-Saron is so powerful that he can break you and destroy your sanity. Phase 2 requires priority on killing tentacles, keeping Sanity as high as possible, and DPS entering portals to attack the Brain of Yogg-Saron. Phase 3 becomes more of a DPS fight, but still maintains Sanity. Every 12 seconds, Yogg-Saron casts Lunatic Gaze; staring into madness itself lowers your Sanity by 4% every second. This is easily countered by turning away; healers must never look at Yogg-Saron and tanks/DPS must quickly turn away. The Normal Mode version allows the four Keepers of Ulduar to assist your raid with various buffs. The Hard Mode versions reduce the number of Keepers as low as the raid wishes, even to, God forbid, zero Keepers for Alone in the Darkness.
  • Argent Confessor Paletress in the Trial of the Champion 5-man dungeon summons a giant shadow creature that casts an area of effect fear spell. Constantly. However, a great portion of the dungeon's difficulty is due to the fact that players treat it as a standard 5-man dungeon despite it being substantially more difficult than anything that came previously.
  • Devourer of Souls in the Forge of Souls is another addition in Patch 3.3.0 that can be a nasty surprise for players used to the relatively easy launch dungeons. He has a hard hitting, fast spell that should be interrupted as often as possible, hard to see area effects and several nasty special abilities that require the whole group to react accordingly. One of them almost always kills the player it aims for, but fortunately its usually only used once at low health. Groups often die to Mirrored Soul, which results in the person being targeted taking damage when the Devourer of Souls does; if the healer dies, the rest of the group soon follows.
  • Keristraza in The Nexus. The party must constantly jump to prevent her Intense Cold debuff from stacking too high, but one of her abilities roots people to the ground. This is also made more difficult by the fact that it is often the first dragon boss that many players who don't raid fight, meaning people need to learn how to avoid her Tail Swipe and breath attacks while DPSing, and the tank needs to turn those away from the rest of the party.
  • The Faction Champions encounter in the Trial of the Crusader raid dungeon is nasty for any group that isn't used to Player Versus Player combat. It consists of a randomly selected group of opposite faction characters who behave like PvP opponents: interrupting spells, using crowd control, and ganging up on individual raid members. The only way to beat them is to keep them crowd controlled while killing the healers, not as easy a task as it sounds.
    • It's also nearly impossible for pugs to complete because Faction Champions requires high levels of coordination. Pugs are not good at coordination.
  • The Beasts of Northrend require a considerable amount of cooperation from all the members, making it difficult for raids with many pick-up members to progress. The first opponent, Gormok the Impaler, throws Snowbolds onto people, which cause damage to players until the DPSers kill them. In the second encounter, Acidmaw hits players with a poison that paralyzes them (before the debuff timer even expires), unless they run over to the tank on Dreadscale who has Burning Bile. The third opponent, Icehowl, is simpler, but if the raid wipes on one of them, they have to start over, and it is impossible to resurrect people between phases except with a Druid's Rebirth. PUGs are very bad idea since Acidmaw for the first half of his fight has a cone area of where his paralyzing poison hits and the said poison drains movement speed until it hits 0. Naturally the raid ends after everyone doesn't realize that they can just face him away from everyone and the kicker is that that was only the second part of the first encounter, you've still got 1 miniboss and 4 bosses left.
  • Icecrown Citadel, being the final major raid dungeon of Wrath, naturally has the most difficult encounters.
    • Lady Deathwhisper could have been considered this before her first phase was nerfed, as coordinating the killing of multiple waves of Mooks, some of which are immune to physical damage and some to magical, while dealing with her Mind Control ability, was tougher than even Blizzard intended. Even after the nerf, she's possibly the most difficult boss of the Storming the Citadel part of the raid.
    • Blood Queen Lana'Thel turns members of the raid into vampires. They get a damage buff, but soon have to bite someone within 10 seconds or get mind-controlled. Getting the damage output to beat her enrage timer involves working out an order of who should be bitten when, then finding the right person to bite before time's up. Losing one person to mind control almost inevitably means a wipe. With 25 people, this gets... interesting.
    • Professor Putricide remains the hardest wing boss thus far, with incredible raid coordination required to deal with all of his abilities, capped off with a severe time limit. Only five guilds managed to defeat him in Heroic mode prior to patch 3.3.3. It's also possibly the most annoying fight in the game for offtanks, who are isolated by being shoved into a vehicle that handles like a cow, where any of their tanking experience is useless, and are given a job where if they are slow on the mark even once the group is doomed, though it may take quite a while for that to become obvious to everyone else. And which the group can make vastly more difficult without even realizing. The fight is also a strenuous DPS race, and not only does he make adds that require the DPS' undivided attention, but in Phase 2, he throws out some of the most crippling damage-reducing debuffs in the game.
    • Sindragosa. While the Lich King himself is harder, he's the Final Boss and wouldn't go on this list. But Sindragosa? Oh, god. A fight that is basically built around RNG. Simply put, the mechanics of Sindragosa demand that everyone in your raid knows what their job is. Now that the Icecrown Citadel buff is up to 30%, any boss before Sindragosa can easily be killed even if people make a few mistakes. However, while learning the fight, you absolutely have to understand the mechanics; if not, you will wipe again, again, and then some more at the same point.
    • The real reason she's That One Boss? "Suffer mortals as your pathetic magic betraaaaaaaaays you!" Not the ability this heralds, (although that's kind of annoying, too) but her voice. Having to listen to that again and again as the raid wipes...
    • Valithria Dreamwalker also qualified as this for solo runs until Patch 6.0.2, as the unique mechanic of the encounter (heal the boss to 100% while adds spawn with increasing frequency) made solo attempts impossible to complete for any class that doesn't have a healing spec. After the aforementioned patch, the door behind her is permanently open, making the fight skippable.

  • Corla, Herald of Twilight, in Blackrock Caverns comes with two Zealots (three on heroic) who turn into powerful drakonids if you don't stand in the way of the beams that are causing them to evolve. The catch? Any party member who stands in them too long will be transformed and mind-controlled, and if someone makes that mistake, it will almost certainly result in a wipe.
    • Corla is one of those bosses that is the bane of PUGs but a joke for coordinated groups, since what she requires players to do is actually extremely easy, but if one person messes it up once, she'll probably kill you. She also requires interrupts to stop her from fearing people through the beams, and while there's nothing stopping you from having a player not stand in any beams and dedicate themselves to interrupting her, in a PUG whether the assigned person will actually do it is always uncertain.
  • Erudax, the last boss of Grim Batol, after casting a large AoE effect that requires people to stack up on a single safe area, summons an add that can release more adds onto the players, and if not killed quickly enough, heals Erudax for 20 percent of his maximum health. On Heroic Mode, there are two of those adds.
  • Ozruk in the Stonecore paralyzes people before launching a powerful attack that can one-shot non-tanks, and the only way to remove the paralysis in time is to get a damage over time spell on you. This is simple for melee classes, as attacking Ozruk causes damage, but ranged classes must reflect their spells off him when he has Elementium Bulwark up so they can get a Damage over Time effect on themselves. Things get tricky for hunters, the only ranged class without spells. On heroic, a tank that understands the mechanics can solo him after the group has gotten themselves killed. For everybody else, he's That One Boss by way of Luck-Based Mission.
  • Admiral Ripsnarl in Deadmines summons many adds that use Cone of Cold on the party and eventually Coalesce and kill everyone in the blast radius if they're allowed to live for too long. Unfortunately, when he appears, people tend to ignore the adds and focus on him, largely because the adds don't do this in the non-heroic version. In that version, they just appear, whack feebly at random people for a bit, and then despawn harmlessly when Ripsnarl decides to reappear.
  • Vanessa Van Cleef in Deadmines; she is only available on Heroic, but is required for completing the dungeon on that difficulty. To even reach her, you must work your way through a room full of fire and collapsing icicles, fight the second boss without aggroing or being killed by the dozens of spiders on the ground, avoid spinning sparks that can kill you instantly and save several NPCs from attacking worgen. The encounter itself is relatively simple, but the detonating explosives (including one she detonates just as she's defeated) can kill you if you're not prepared.
  • Heroic Deadmines also features the Foe Reaver 5000, boss number 3 in the line-up. First up, one of the 3 dps must jump into a vehicle to manage adds throughout the fight who will wipe the group if they reach the party, and after 2-3 of them are coming at once it gets tricky at best to do so. Because of the adds, he needs to be pulled up the ramp and killed there, limiting the fight to narrow quarters, which makes it difficult to avoid his two attacks that will decimate anything near him (and one of them requires the group to haul ass away from a spot before he charges to it). Not fun.
  • Baron Ashbury in Shadowfang Keep. The fight isn't particularly healing intensive nor tanking intensive. However, the fight rests almost solely on your DPS to interrupt Ashbury's heals with Stay of Execution and Mend Rotting Flesh. If your DPS doesn't interrupt, you will eventually wipe. This fight becomes a god-awful nightmare in pugs because most pug dps are just not capable of interrupting spells. Thankfully, his worst ability, Mend Rotten Flesh, has been removed. Since he would often cast it immediately after Stay of Execution, and Pain and Suffering can't be ignored, either, victory was impossible without three people who could interrupt on a regular basis, and many groups only had two people who had the capacity to do so, meaning that they would likely fail regardless of their players' skill at interrupting.
  • Lord Godfrey is only moderately difficult as a Heroic boss at level 85, but when players go through normal Shadowfang Keep in their late teens and 20s, his abilities (summoning adds, placing a DOT on random people with Cursed Bullet, and a frontal cone AoE that almost certainly kills those standing in it) are considerably more complex than most other boss fights around that level, even compared to many of the other bosses in the revamped Deadmines and Shadowfang Keep, who do not have their most deadly abilities in Normal. Cursed Bullet is especially difficult, since your party will likely be unable to interrupt or remove the curse like a level 85 group can.
    • Cursed Bullets should probably be singled out, because unlike other "mandatory dispel" mechanics in Cataclysm it is a curse, meaning paladin healers cannot dispel it at all, level 85 or otherwise. The encounter comes down to the tank and DPS interrupting the quick, frequent casts and dispelling the ones that go through...or forcing the paladin to heal through increasing shadow damage on multiple players. This is no mean feat when said inexperienced/lazy players are taking damage from the Pistol Barrage as well.
  • Jin'do the Godbreaker's first phase is quite easy, but in the second, players must trick Gurubashi Spirits into using Body Slam on the chains binding Hakkar while dealing with many adds. If a Body Slam doesn't hit a chain, it can easily mean a wipe.
    • There's a reason he was widely known as 'Jin'do the PUGbreaker' for a few months after his dungeon was released, which is saying something considering the general difficulty of Cataclysm-era 5-mans.
  • The Conclave of Wind in Throne of the Four Winds can cast a raid-wiping debuff if no one is on one of the platforms at any given time. This can obviously happen if all of that platform's group is dead, but it can also happen if everyone gets blown off Rohash's platforms or if a platform switch isn't properly timed. They must also be killed within 60 seconds of each other- a stipulation typically applying to some boss achievements- or they will come back with full health. As a result, it's very easy to make a small mistake and quickly end up with an Unwinnable fight.
  • Chimaeron in Blackwing Descent presents healers with a unique challenge. The players receive a buff that enables them to survive any attack while being reduced to 1 HP as long as they are at over 10,000 HP. The damage is so high during the fight that any more than this is wasteful. However, Chimaeron will frequently disable the buff, forcing the healers to restore the entire raid to full in order to survive. The fight comes down to their ability to quickly and efficiently maintain the raid at just over 10,000 HP in preparation for the burst healing phase, whereupon they pop mitigation cooldowns and heal like mad. While the fight is not especially hard for DPS, healer mistakes can easily lead to deaths, and a party with missing players cannot beat phase two (where everyone becomes immune to healing).
  • Nefarian in Blackwing Descent is quite possibly the hardest normal mode boss of the tier. In the first phase, you have to put as much damage on Nefarian as possible while killing Onyxia before she explodes and wipes the raid and dealing with the adds. In the second phase, you must quickly swim through lava to reach platforms while splitting up into three groups so that you can kill the adds. The third phase is relatively straightforward, but if the Shadowflame is poorly handled, it can reanimate the adds or kill the raid.
  • In Firelands, prior to the nerfs, Baleroc was one of these if you're a healer. His signature mechanic consists of putting a buff on the player who is tanking him, which increases his/her health exponentially. Healing players afflicted with Torment grants the healer a stacking buff, which turns into increased spellpower when the healer returns to the tank. The healer cannot increase their stacks any further while the healing buff is active, so they must coordinate with the other healers to make sure the tank is always being healed, the Tormented players are always being healed, and no healer's buff falls so far behind the tank's health stacking that healing becomes impossible.
  • Beth'tilac in the Firelands. While the DPS requirement is lenient enough that people can send the minimum of a healer and tank up top while everyone else stays down below, the adds are quite difficult. First, the Spinners can only be brought down with a taunt, and if left up, will do severe damage to everyone in the raid. Swarms of Spiderlings come out and must be AoEd down, or else they will heal and buff the Drones, enabling them to go up top and shorten the first phases of the fight, giving you less time to kill the adds before Beth'tilac comes down. Another problem is that if the healer for the group up top goes up first, or the tank goes up too far in advance, one of them will die, Beth'tilac will then kill the other, then the rest of the raid will wipe from Beth'tilac's raid-wide attack once no one is up top.
  • The fight agains Ragnaros in the Firelands has three phases, and while the first phase is fairly easy, the second and third require good positioning to avoid wiping on the Searing Seeds, and quite a bit of movement when you're faced with the Engulfing Flame and Living Meteors. Perhaps the worst part of the fight comes in the transition phase, when eight Sons of Flame come out, and if one reaches the hammer, the group will most likely wipe. Not only does this require extensive coordination, but it's also something of a Luck-Based Mission, as the hammer landing in the center makes it more difficult to kill the adds in time.
    • Not to mention that HEROIC Ragnaros 25 man required you to run it with 3-4 healers(due to the RIDICULOUS DPS requirement), added another entirely new phase that was entirely based around RNG(who meteors would target, where roots would spawn, where fires spawn and where breaths would spawn) and if one member of your raid is out of position, you are royally screwed and wipe.
  • Echo of Tyrande in End Time can use many attacks that silence her enemies and are difficult to avoid. It's thus difficult to heal and avoid those projectiles at the same time, and if a healer gets silenced too often, it will result in a wipe.
  • Dragon Soul gives us the delightful Warlord Zon'ozz, who casts an enormous purple ping pong ball that must be bounced between targets before being rebounded to the boss. Bounces do AoE damage, which splits among targets and must be soaked. If the ball doesn't bounce enough times before returning to him, Zon'ozz cannot be killed before he enrages. If it hits the wall, he enrages instantly. He casts a damage over time debuff which, when dispelled, explodes and sends the target flying, but dispelling is mandatory due to the DoT. If the player's health is too low the explosion kills them, and if they are thrown into the ball they bounce it alone and everyone dies. Oh yeah, and the ball appears to move several yards forward after the game registers the bounce, it has a tendency to careen in a random direction (forcing the waiting raid members to dash over and catch it, or the tank to pull the boss over before it can hit a party member), and anyone caught in his frontal cone attack heals him. All this from either the second or third boss of the raid, and Hagara (#4) is laughably easy in comparison.
  • Yor'sahj the Unsleeping can be quite difficult for groups that aren't well coordinated. He sends out three slimes, only one of which can be killed (and it takes all the DPS to kill it before reaching him), which give him various buffs. Some of these buffs obviously are bad combimations, such as having green and red together (the former forces you to spread out while the latter forces you to stack), and some are clearly worse than others (especially purple, which makes people explode every fifth heal). A kill order must be worked out, and if he gets the wrong buffs or somehow gets all three, you'll likely wipe.
    • The real That One Bossitude of Yor'sahj comes from that the priority of slime killing will be completely different depending on the difficulty setting your raid team is using for the encounter. On LFR difficulty, getting rid of purple slimes is the most important, since one healer not knowing what they're doing can easily cause a total party wipe. However, green and red slimes at the same time is no big deal since green doesn't do significant splash damage on that difficulty level. On normal and heroic mode, however, the purple debuff isn't so bad (especially if paired with the blue slime, since you're not in danger of setting off the debuff if you don't have the mana to do much healing), and healers get used to healing around it, but combining red and green together would only work if you have a very melee heavy party. Get a raid leader in normal calling out slime priorities like it's LFR or vice versa and you're in for an exciting ride. And on heroic, he summons FOUR slimes, so raid groups HAVE to deal with at least three buffs on Yor'sahj.
  • Spine of Deathwing is generally considered the hardest Dragon Soul boss due to the large amount of coordination involved and the many things that can go wrong. If you don't interrupt the Corruption's Fiery Grip, it can cause problems; if you accidentally kill a Corruption, you end up with an extra Hideous Amalgamation. If you kill an Amalgamation before it has 9 stacks, it won't blow open one of the plates; if you give it 9 stacks when it has too much health, the raid takes considerably more damage.
    • Come Warlords of Draenor, the bosses of Dragon Soul became easily soloable by max-level players... with the exception of Spine of Deathwing. With only one player present, Deathwing threatens to roll constantly, requiring you to run back and forth between his left and right sides, all the while pulling off the add management necessary to clear the encounter. Stay in one place for too long and it's instant graveyard run time for you.
  • Nyxondra, a boss in an individual quest chain in the Badlands. Some genius at blizzard thought it'd be a very good idea to put her in a valley full of whelplings when you're with three vikings/orc commandos. The vikings/orc commandos have a tendency to aggro everything in sight, especially when they get feared. Who thought that was a good idea?
    • The three vikings/orc commandos also take the place of your pet, so they become doubly annoying for hunters and warlocks, who could probably kill Nyxondra much faster if they had their actual sidekicks with them.
    • It's something of adding insult to injury that the bizarre pet mechanics forced on you for the fight are a joking reference to another video game entirely. It was admittedly very funny, if you were one of the ones who played said game back in 1992 — before much of Blizzard's audience had even been born.
  • Ruuzel in Ashenvale is possibly the hardest low-level world mob in the game, that is, if you're a caster. If you use melee, she's nothing too difficult, but lord help you if you're a caster. You see, aside from just hitting you with her staff, her only two spells both interrupt casting, one of which is just a green Death Grip that she'll use if you get too far away from her, and the other is a melee with a knockback, that she will spam every 2-4 seconds. If you don't have access to too many spells with a cast time of less than two seconds, the fight is practically impossible.
  • Assuming they weren't this to begin with, every boss in End Time definitely became this when Warlords of Draenor introduced Timewalking: events that allow players to tackle low-level dungeons with their levels and gear scaled down accordingly. Unfortunately, initially the item level your gear scaled down to was the same for all Cataclysm era dungeons, in spite of End Time being an endgame dungeon while the rest were launch dungeons. This, combined with the fact that many players thought the Timewalking dungeons would require little strategy besides Zerg Rush, made End Time a pain in the rear until Blizzard hotfixed the item levels to scale to a more reasonable level.

    Mists of Pandaria 
  • World Boss Sha of Anger can be this. One of the most common pieces of advice for the fight is "run back as soon as you die". Special mention goes to a monstrous number of Adds and regularly mind controlling three players while increasing their health and damage to five times normal.
  • The Stone Guard is a difficult coordination fight, as you must ensure that the one casting petrify is the only one that overloads, or else you will take more damage than you can afford; this involves a fairly complicated tank swap very quickly at several points per attempt. There is also a bit of luck involved; in the 10 man version, the set of guardians for the week can determine your chances of success; having the Jasper Guardian up makes things significantly more difficult, as it forces certain raid members to stay together or take severe damage.
  • Elegon is quite possibly the hardest boss in Mogu'shan Vaults. If you don't kill enough waves of adds and aren't able to put out enough damage, you will not be able to survive the last phase of the battle.
  • Garalon is easily the hardest boss of Heart of Fear for PUG groups. Tight positioning needed to stay in the damage buff zones, which also overlap with a do-not-enter zone that will cause a whole-raid AoE if anyone steps in it, meaning a single clueless person can result in a wipe. Another problem is that he is not tanked in a conventional way; one player kites him by moving around with Pheromones while the boss fixates on that person, while two tanks must stay in front of the boss to prevent it from getting a damage and movement speed increase buff; someone making a mistake can easily result in people winding up in the Crush zone. Also, Pheromones causes a raid wide DoT that increases over time, another player has to trade Pheromones with the first to reset the DoT, otherwise the damage Pheromones deals to the raid becomes unhealable. It also doesn't help that he initially had more HP than was reasonable for LFR until he was hotfixed, and further fixes capped the Pheromones DoT and put a cooldown on Crush.
    • Although that last was more to make it harder for Jerkass players to intentionally wipe the PUG by standing underneath Garalon, causing him to spam Crush.
  • Besides Garalon, Amber Shaper Un'sok is particularly hated by both pugs and organized groups. While most of his abilities are rather easy to deal with, his most dangerous one Reshape Life, which changes a random raid member into a monster. The affected player then has to pay close attention to their actions, since they will periodically automatically cast an AoE ability that will damage the entire raid unless they manually interrupt it, and doing so eats up Willpower, and if you run out of Willpower, you become mindcontrolled and hostile. Also, the raid has to time the transition to phase 2 right, because the Amber Monstrosity that spawns in phase 2 casts the same AoE ability which can only be interrupted by players affected with Reshape Life, so if your timing is off you could have the Amber Monstrosity dealing massive AoE damage in between Reshape Life casts, often leading to wipes. On top of all of that, the only way to break a player out of Reshape Life is to bring them down to below 20% health, where the player then has to manually break out. The problem is that if the player is too slow, or the raid doesn't control their dps, they're very likely to get killed by their own raid. Basically, this fight is so hated because the smallest slip up can wipe the raid, and there is a LOT of potential for that.
  • GG Engineering, the first Rank 7 fight in the Brawler's Guild, requires you to put out 12 million HP in damage within two minutes while dodging deadly rocket blasts. To make matters worse, every 20 percent of their health you take off one of them goes under a shield that must be destroyed.
    • Unless you take the smarter route of staying close to the gnome to make the goblin rocket blasts hit him. The damage from the rockets is so high that it allows you to bypass the dps requirements, you can even not dps at all and still kill them as they have shared hp. Alas, this method still has the drawback that it's dependant of your connection speed/processing speed, as if you get hit by a single rocket, you will most likely die unless you are playing a class that has abilities that allows them to negate damage or survive would-be fatal hits (self resurrection abilities do not count, sorry).
  • Immediately after GG Engineering comes the Dark Summoner fight, in which you must kill ghost adds in order to render the boss vulnerable. This wouldn't be so hard, but the ghosts can kill you in one hit and have a large attack range, two factors that make the fight significantly more difficult for melee classes. To top it off, the ghosts are very hard to see (unless you turn on enemy nameplates), and it's entirely possible for them to spawn right on top of you, killing you instantly.
  • Oondasta, one of the world bosses in Patch 5.2.0, seems to be designed to be That One Boss by Blizzard. Not only does he have a tank swap mechanic combined with an immunity to taunt, a Frill Blast that kills non-tanks, a chain-lightning Spiritfire Beam that kills its victims after the first few hits, and a devastating raid wide AoE Piercing Roar, but he also has a soft enrage mechanic that gradually increases his damage. Graveyard zerging only gets you so far when eventually, even Piercing Roar can one-shot you. Relatively soon after he came out, Blizzard decided to cut his health in half, but even so, he still typically requires multiple full raid groups to defeat.
    • Oondasta was supposed to be doable by a dedicated raid group, and was put there as a challenge for hardcore raid teams to beat. However, because it was out in the open a viable strategy was to Zerg Rush it with hundreds of players all at once, and this proved too much for the servers to handle. Oondasta wasn't nerfed because the developers thought he was unfair, he was nerfed because Blizzard put the beast where hundreds of non-raiders could find him.
  • Also from 5.2, the Warlock-exclusive Kanrethad Ebonlocke, who rewards warlocks with green fire... If they can dodge all his one-shot mechanics while also DPSing enough to beat the enrage timer. Kanrethad Ebonlocke is THE One Boss for the warlock class. He's only available by a class-locked special warlock mission, which means he must be fought alone, without support of tanks or healing. He was specifically designed with a plethora of complicated mechanics designed to force the warlock to use each and every last one of their special warlock tricks, and is really only defeatable by a specific spec (which means if you were more practiced in Affliction or Demonology, you have to re-learn your entire way of fighting.) Among the mechanics you have to master for Kanrethad include:
    • He opens the fight by summoning a giant Pit Lord that can one-shot you. You must Enslave the pit lord before it can hit you (which also means you'll be short your accustomed tanking or DPS pet for the rest of the fight.)
    • For the rest of the fight, you must manage the Pit Lord's abilities on top of your own, which include a critically-timed interrupt (if you miss it, you'll die; if you hit it too soon and it's on cooldown when you need it, you'll die,) a stacking buff that MUST be properly stacked every.single.time., AND a cleansing spell which is vital for your survival later in the fight.
    • The boss himself has both a nuke spell which will kill you unless it is interrupted, AND a nuke spell which will kill you unless you hide from its line of sight; you can't interrupt both. This means you have to use the warlock's distance-skipping portal abilities to blink around the battlefield in order to make it to cover in time (and God help you if your 'run for cover' abilities are on cooldown when you need them.)
    • He also puts a DOT on you that will periodically and randomly stun you for multiple seconds — where a second's inattention can cost you the fight — unless you can get it off yourself by running in front of your Pit Lord while ordering it to cast cleansing fire.
    • And he's not done yet! His next trick is to summon fel hunters which can purge spells... INCLUDING the spell you're using to Enslave your pit lord; if your Pit Lord breaks free, you have less than three seconds to restore it before it kills you (and the felhunters will just purge your spell again unless you can kill them.) Did I say fel 'hunters' plural? Yes, because he summons TWO! You have to Banish one, then kill the other, then release and kill the first, before either of them can get their tentacles on your pit lord. You generally have to order your pit lord to move to the opposite side of the room when the fel hunters come out, then move him back to the middle after they're dead BUT before the boss can do his must-be-interrupted nuke.
    • I'm not even bothering to mention the waves of nearly 50 imps at a time, because compared to the rest of this fight, they're easy.
    • And we're still not done because here comes phase 3! He summons ANOTHER Pit Lord, and you cannot enslave two at once; you have to Banish the second. And then he summons a Dreadlord, which you must control by keeping Feared... and then another...
    • Meanwhile, all the while you're directing your Pit Lord around the battlefield, keeping an eye on Kanrethad's nuke timers and a finger on the interrupt button, being ready to bolt for cover on a dime, pumping out massive AOE damage to kill the literally dozens of imps, pumping out massive burst damage to kill the felhunters before they can free your pit lord, cleansing yourself of the Do T, and being fast as a snake on the target switching and various crowd control mechanics, you have to manage, you ALSO have to maintain an extremely high output of DPS on Kanrethad himself, because if you don't kill him within a certain time frame, you automatically die from his Curse of Doom spell.
    • It's worth noting that while higher gear levels within the bracket could help ease the time choke a little, this was a limited-run questline which became unavailable in the next expac, so there were never any opportunities to go back and do it later; this boss could only be fought at-level.
    • In short: if you see a Warlock in the world with the Green Fire appearance modification and the "of the Black Harvest" title, give them a salute. Because they've earned it.
  • Tortos in Throne of Thunder has a Quake Stomp that does almost two thirds of the victims' maximum health, Vampire Bat adds that heal themselves, and a Furious Stone Breath that will wipe the raid unless you defeat one of the turtles (which spin around at people, causing damage and throwing them into the air) and kick the shell into him. Groups that are still learning him often wipe very early on in the fight, and if a Furious Stone Breath isn't interrupted immediately, your group will wipe.
  • Durumu in Throne of Thunder is considered one of the hardest fights in the tier, especially in LFR. Most of his abilities aren't too hard to deal with, but he has two major phases. In one phase, he sends down adds that can only be exposed by a cone of light that damages everyone in it; two beams follow certain players, while the third moves on its own. In LFR, the phase only ends when one add of each color is killed, and since the yellow add can only be killed when the beam uncovers it, it's a Luck-Based Mission. In Normal, if any of the beams goes off the add in question, the raid will take a large amount of damage and wipe. He will also lay down a maze of Eye Sores that kill people almost instantly while forcing people to run around him with a beam that kills anything in its path, while also contending with voidzones left earlier in the battle. Part of the problem here is that it's often difficult to tell where you need to start, and if you start in the wrong place, you will die very quickly; in some LFR attempts, the entire group perishes almost immediately due to being out of position.
  • Lei Shen is by far the most frustrating fight in Throne of Thunder. Basically, literally every single one of his abilities deals massive AoE damage to the raid, which he casts often and get progressively more powerful as the fight continues. Not to mention, he will also start to electrify parts of the floor, severely restricting your room to maneuver. The transition phase is also the most challenging part of the fight- he unleashes the abilities of all four quadrants at once, forcing you to divide your raid between the non-electrified quadrants while soaking Bouncing Bolts and Static Shocks, and avoiding getting stunned by Overcharge or getting excess adds off Diffusion Chain. Depending on RNG, you can get few or many special abilities per quadrant, and they may or may not be inconveniently timed (a Diffusion Chain while the people in one quadrant stack to avoid Overcharge, or Bouncing Bolts on opposite ends of the quadrant while one person has Static Shock). His final phase is further complicated by powerful winds periodically blowing across the platform, which can make it very difficult to escape the more punishing AoE effects.
  • Hexos, the first Rank 8 Boss in the Brawler's Guild, must be rapidly turned so that he doesn't collide with any of the pink walls that are closing in, while still being killed before the time expires. To make matters worse, he's the first boss in the tier, meaning that he comes after the relatively easy Meatball and is the first boss those who have maxed out their rank face once they re-enter the Brawler's Guild in 5.3.
  • Dippy, the First rank 2 boss and a Wake-Up Call Boss of the grandest scale, he has a uninteruptable spell called "peck" with 2 seconds of cooldown, which instant kills you. The only way to survive is to beat him every time he gets into range, hence pushing him back and interrupting peck. While this is obscenely easy for rogues or druids who can just autoattack every time, it's an absolute nightmare for Paladins, who have massive gaping holes in their rotations where their utility spells are supposed to go. Furthermore, if you back him up to a wall, he'll instantly kill you.
    • To make matters worse, there's a challenge card that puts you against Dippy and Doopy. Even if you know the trick, failing to pay close enough attention to both of them will result in one killing you.
  • Nibbleh, the second Rank 9 boss, lays puddles of poison on the ground wherever he goes. They have an effect beyond the typical damage; if he stands in them, even for a moment, he gets a permanent buff that increases his damage and allows him to quickly kill you. Essentially, you have to kite him around to avoid dying, and DPS hard to avoid running out of space.
  • Thok the Bloodthirsty in Siege of Orgrimmar alternates between two phases- one in which he uses a spell that does large amounts of raid wide damage while interrupting casting repeatedly (in addition to other abilities), and one in which he chases random raid members around, growing faster over time and killing anyone he catches instantly. The fight is a severe gear check, and if you make a simple mistake, such as letting too many people fall below half health (the prerequisite for changing phases) in the first phase or getting eaten by Thok in the second phase, you will pay dearly, and most likely wipe.
  • Siegecrafter Blackfuse is one due to huge amounts of ads and many different types of AoE often at the same time. The fight starts where he launches buzzsaws at random players which then stay in place and damage anyone near them. DPS also have to get on the conveyor belts and destroy ads such as death rays and bombs but you can't get them all. He eventually summons a shredder that gets healed if it gets too close to Blackfuse and can do a lot of AoE damage with Death From Above. Things really get nasty when Blackfuse starts doing a spreading wave of AoE damage with underground drills that also throw the player into the air. At the same time you still have to avoid buzzsaws and walking bomb ads that follow random players and detonate with the potential for one hit kills. Then he has a magnet pull the buzzsaws and the players away while still dishing out ads and AoE. Many raid groups doing Downfall have ragequit because they can't get past this boss.
  • Paragons of the Klaxxi is perhaps one of the most complicated fights ever introduced. It consists of nine bosses, with three being fought at any given time and no clues as to what order they will enter the battle (the order at least stays the same in any given week, but can change from one week to the next). Each boss has their own handful of different abilities. Many of these will do massive damage if you don't know what you are doing. Some will heal the bosses if you don't know what you are doing. Some will crush the tank if you don't remember the arbitrary pairings that cannot be tanked together. All will drop a bonus orb when they die that gives some players extra abilities at the cost of complicating the fight even further. When one boss dies it will buff the other two that were fighting with it, meaning that the kill order is dependent on the number of buff stacks each has as well as how annoying each boss is on its own. Most players will need to have at least some understanding of what each boss can do, and guide videos are unlikely to fall under the thirty minute mark.
    • Special mention must go to Iyyokuk the Lucid whose aptly-named Insane Calculation ability would be sufficiently complicated for him to be a boss on his own. He gives every player a different debuff that has a random color, number and shape associated with it. He then picks a random player and connects them to every other player that shares the same color, number or shape with a flaming tether. Players need to figure this out in time and spread away from each other to lessen the damage, and even the unaffected players must try to dodge the fire.

     Warlords of Draenor 

  • Warlords of Draenor brings us Imperator Mar'gok. On the surface, he's simple, with only five or so abilities, all of which can be mitigated or avoided entirely. However, as the (very very long) fight goes on, his abilities become more and more hectic and difficult to handle. And handle it you must, for if anyone - ANYONE - mishandles his abilities, then the entire raid can die as a result. As for the abilities themselves, there's mines which explode when stepped on (and later on in the fight duplicate themselves) adds which harm the raid when alive, and explode when killed (in phase 2 knocking people back when doing so, sometimes into the aforementioned mines), a stacking debuff which passes from player to player via proximity (and in phase 2, the person who has it cannot move, meaning everyone else must flee from them). A debuff placed on one of the tanks which causes anybody within a large range of them to explode (and in phase 3, this tank cannot move, once again meaning everyone must flee from them), and a circle of deadly energy which harms anybody who steps through it - though stepping through it is unavoidable, and one must simply run through it as quickly as possible. All in all, these abilities are not too difficult to deal with, but the fact that a single mistake can easily snowball into death for the whole raid means that groups who would otherwise defeat the previous six bosses with ease can very quickly run into a wall with this guy.
  • The 5-man dungeon Bloodmaul Slag Mines has Roltall. The fight takes place on a wooden bridge against a giant fire elemental - already you can tell where the problems might arise. His main ability sends a giant boulder down the bridge; there's enough room for 3 boulders to go down, and he will send them down each third in a random order. Big deal, right, just dodge them and keep going...but on heroic difficulty the boulders come back along the same path, pretty quickly to boot, requiring players to memorize the order they came in and move perfectly between the boulders of death. It often happens that one boulder is going down at the same time the one next to it is coming back. To add to this, fire will spread throughout the bridge and fairly quickly reduce the space you have to move between the boulders trying to kill you. The only way to circumvent this is to perfectly dodge all the boulders and avoid the fire and DPS the boss fast enough so that the entire bridge doesn't get covered in flames.
  • Orebender Gor'ashan stands on a raised platform and summons energy into power conduits that reduce his damage taken and allows him to cast a spell that damages everyone in the room. Players have to run around the lower section to deactivate these conduits. They have to dodge lightning orbs that do massive amounts of damage, and often run out of the line of sight of the healer while doing this, so it's not rare for everyone except the tank to die. At which point a well-geared tank is left with the grueling task of soloing the guy, who if allowed to keep casting his area of effect spell deals an indefinitely survivable amount of damage to a tank, but has huge damage reduction and quite a lot of health.
  • The Blackrock Foundry is full of difficult bosses, but the runaway hardest (not including the final boss) is the Blast Furnace. It's a three-phase fight that requires precise execution to defeat. The first phase involves the raid splitting into two groups, killing adds before they can apply heat to the furnace, as well as adds that drop bags of bombs needed to damage the furnace. Once that messy business is done, the 2nd phase involves the big Fire Elemental inside the furnace being protected by Primal Elementalists, which are themselves immune to damage. How do you make them vulnerable? By killing a certain type of add, Slag Elementals, right next to them, making them vulnerable for a stingy 15 seconds. While this is going on, there's a constant stream of adds that themselves do nasty things to the raid and must be killed. Once all the Elementalists are finally dead, you get to fight the actual boss. This phase is pretty simple. Kill the fire elemental before it kills you. The thing is, the longer you spent doing the first 2 phases, the more powerful the boss is. As such, the majority of the challenge in this fight is doing the first 2 phases efficiently. But that's more than enough.
  • The Iron Maidens are easily the third hardest boss after Blackhand and the Blast Furnace. The fight is fairly easy at first, but as the three bosses lose health (unlike some "council" fights, you have to be careful to take them down at roughly the same rate), they unlock new abilities as time goes on. Some of those attacks are standard fare, but it quickly gets complicated when they overlap (for example, stacking on Gar'an's beam to split the damage becomes quite hard when the ship's shooting bombs, and the stack point is near one, or when some of the people get targeted by Bloodsoaked Heartseekers and have to spread out). The final 20% of the fight becomes extremely hectic as all three gain access to their strongest abilities, and inflict incredibly high raid-wide damage.
  • Hellfire Citadel was full of so many of these bosses that the entire Normal Mode had to be toned down! Where to begin...
    • Kilrogg Deadeye was the first real brick wall of the raid, and a shining example of just how unforgiving Hellfire Citadel could be. He shouldn't be that hard, in theory, as just about everything bad is avoidable. The problem is that one mistake can wipe the entire raid. If a Bloodthirsting Salivater gets to the fel pool, you die. If a Hulking Terror's Rending Howl doesn't get interrupted, you die. If too many people get hit by Heartseeker at once, you die. If a group misses the Visions of Death portals, you die slowly, since you won't have anyone to purify the Fel Corruption, resulting in mind controlled tanks.
    • Shadow-Lord Iskar introduces one of the most annoying mechanics ever conceived in World of Warcraft: the Eye of Anzu. It deals raid-wide damage unless a party member holds it, and it can't be held for too long by a single party member or they will die. Iskar creates winds that will blow party members off the platform unless they are holding the Eye of Anzu, and as such it has to be passed from person to person so that no one flies off. Needless to say, this requires the entire raid to be on the ball so that the winds are dispelled quickly. Once the adds show up, however, things start going downhill very quickly. Three types of adds show up, and each requires a specific party member to hold the Eye at a specific time to dispel or interrupt their abilities to prevent a very quick raid wipe. The Eye of Anzu is so annoying to deal with that it's practically mandatory for the entire raid to use a specific mod to make passing the Eye easier (Iskar Assist).
    • Tyrant Velhari seems easy in comparison to most of the bosses in the raid. While nearly every boss in Hellfire Citadel is a massive Flunky Boss, Tyrant only summons one add at a time. The real problem, however, is that Tyrant is a strict gear-check boss. Phase 2 introduces an aura that lowers your maximum HP over time, to as low as 15%. If Phase 2 isn't dealt with quickly enough, the raid will wipe. While you could Heroism/Bloodlust/Time Warp to make that phase a little faster, Phase 3 isn't much better, since in that phase players will gain a stacking debuff that causes them to deal and take more damage over time. Pick your poison.
    • Next to Archimonde, Xhul'horac is the most chaotic fight in the entire raid. He applies debuffs on players that cause them to drop either green or purple fire on the ground that rapidly spreads. The catch is that if green and purple flames come into contact with one another, or if a player with a green debuff steps in purple fire or vice versa, it results in a massive explosion that hits the entire raid. Then there's the adds. While most bosses in Hellfire Citadel are Flunky Bosses, Xhul'horac is undoubtedly the worst of them all. He summons both imps and voidwalkers, each of which can leave green or purple fire respectively on the ground by themselves if players don't react to them quickly enough. Phase 2 is where things start to get ugly, because in that phase Xhul'horac will begin to summon voidwalkers and debuff players with purple fire, but the imps from Phase 1 that leave behind green fire are still coming! Lots and lots of explosions can result if the imps aren't dealt with quickly enough.

  • Cenarius is easily the most difficult boss of the Emerald Nightmare, simply because of the sheer amount of mechanics that need to be addressed. If a Twisted Sister gets off too many casts of Scorned Touch, you die. If a dragon gets off too many AOE casts, you die. If you're not paying attention to your Nightmare Corruption and don't get into the green pools before the damage become unhealable, you die. If you don't have the DPS and the kiting skills to kill the boss in Phase 3 when he starts covering the entire arena in a deadly void zone, you die. If not enough Brambles are cleared, you'll die as your entire raid gets caught in them while dealing with everything else.
  • Helya, introduced in the Trial of Valor raid, is easily one of the most difficult bosses of the expansion yet. It combines tons of add control, target switching, and instant-death mechanics for a boss that is the definition of pain incarnate. It's notorious for being the bane of PUG groups everywhere; it's quite difficult even with a well-coordinated raid.
  • Due to the Dynamic Difficulty nature of Mythic+ dungeons, almost all bosses have the potential to qualify as this. Some reach this point on far lower levels than others however.
    • Cordana Felsong in the Vault of the Wardens isn't necessarily that bad, but if the group you're with doesn't know how to use Elune's Light, you're SOL. If you've got an organized group she's pretty trivial, but if there's one thing pick-up groups of random players struggle with, it's mechanics they can't just DPS through.
    • Before her, there is the second boss, Inquisitor Tormentorum. The fight consists of virtually everything to make it a nightmare: multiple debuffs (including, slower movement, disorientation, and gradual petrification, a special atttack called Sap Soul, which prevents players from using one of their abilities and which CANNOT be interrupted on Mythic difficulty, additional varying trash mobs... You'll grow to hate the phrase "Your souls are mine!" because of him.
    • Hymdall is mostly an awareness check. His Bloodletting Sweep will likely oneshot any non-tank players who find themselves in front of him, and his Storm Breath will certainly oneshot non-tanks. In addition to this, his Horn of Valor deals high aoe damage to all players, and standing in his whirling blade will kill you in seconds.
    • Hyrja is likely the most dangerous boss in Halls of Valor. Her Eye of the Storm and Arcing Bolt abilities are gradually empowered the longer she stays on the left side of the room, and her Sanctify and Expel Light increase in damage in the same way the longer she stays on the right side. Eye of the Storm deals aoe damage over time for around 5 seconds, and she immediately follows it up with an Arcing Bolt which can easily finish off players that haven't been kept topped off.
    • The Wrath of Azshara in Eye of Azshara can be dangerous due to the sheer amount of spells you need to avoid, especially considering taking damage from a spell increases the magic damage of that school you take for the rest of the fight, and that the damage from Crushing Depths is split between all players, meaning it becomes more lethal with more group members that die. It's especially dangerous if the level 2 affix is Grievous, as is makes the already high healing requirement even more demanding.
    • Talixae Flamewreath is dangerous for two reasons; the imp adds she continuously spawns and the ever increasing aoe damage she puts out. The former is likely to cause more danger if you lack the CC, damage, or both required to deal with them safely.
    • Shade of Xavius has a wide variety of abilities that single out a player and deal significant damage or affect them in other ways. Nightmare Bolt hits hard and pacifies the player for a while unless they're standing close to another player. Conversely, Growing Paranoia will fear the target if they stand close to anybody else. Feed on the Weak is a very strong channelled spell that demands strong single target healing. At 50% health, Xavius casts Apocalyptic Nightmare which players will need defensives to survive at higher keystone levels. From here on out,the fight becomes significantly more dangerous, as players will now need to avoid swirlies on the ground, as well keep Xavius from being hit by them; any time he stands in a swirlie, he gains a stacking damage buff. This causes Nightmare Bolt and Feed on the Weak to become potential oneshots (if they weren't already).
    • Moroes fights alongside his dinner quests, who all have a variety of dangerous abilities, such as a spinning axe that deals strong aoe damage to those too close, a mana drain that stuns your healer and depletes them entirely of mana if the whole cast goes through, and a frontal aoe that comes fast and has the potential to oneshot. The catch is that these dinner guests can be CC'ed before pulling Moroes, and can be CC'ed until Moroes reaches 60% and frees them. Therefore, the key to defeating him is to CC his guests and deal with them in a controlled fashion. Don't take too long however; Moroes periodically applies stacks of Garrote on random players, which causes them to take bleed damage for the rest of the encounter.
    • Harbaron can be difficult on a similar vein to Hymdall - the majority of deaths will be from his scythe attack that becomes lethal at higher keystone levels. It becomes a hectic fight when you also have to deal with his adds - one of which who will aoe the whole group if not interrupted, and the Fragments that stun and deal high single target damage to a player.
    • Shade of Medivh requires a mix of high dps, high healing and excellent coordination on higher keystone levels. Frostbite hits players hard and keeps them stunned until another player gets target by Inferno Bolt and gets them hit by it too. Inferno Bolt itself deals fairly high damage overtime, and Piercing Missiles hits the tank hard and if fully channelled, causes the tank to take additional damage from the next cast. Even more dangerous are his three ultimate abilities; Flame Wreath targets two players and places a ring around them. These players take high damage for 20 seconds, and accidentally stepping outside the ring instantly kills the group. Ceaseless Winter will make quick work of players unless they keep moving, and Guardian's Image summons three arcane birds that deal increasing aoe damage to all group members until killed. The difficulty of this boss can greatly fluctuate based on the amount of interrupts you have, your group composition, and luck.
    • Viz'aduum the Watcher is the last boss of Karazhan, and is difficult to match. The fight has three phases, the first of which isn't so bad due to how much room the group has to work with. Players must avoid swirlies on the ground and not stand in front of him when he casts Disintegration. The most dangerous mechanic at this point is Chaotic Shadows, which deals ticking damage to one player and once it expires or is dispelled, sends deadly orbs in multiple directions. Upon reaching 66% health, the boss retreats to a ship and the players must follow him through a portal, then avoid being hit by Disintegration on the way back to him. Here, the group has much less room to work with, and Chaotic Shadows affects two players, up from one. At 33%, he retreats to his last ship, and the group must now fight through a load of adds. On this final platform, Chaotic Shadows targets three players, meaning the group must stay sharp and manage their space well.
    • Oh boy, Seat of the Triumvirate. While Zuraal the Ascended is comparatively easy, the rest of the bosses can even give a coordinated group a run for their money.
      • Saprish fights alongside his pets, Shadewing and Darkfang. Shadewing periodically leaps to the furthest player and attempts to cast Dread Screech, which disorientates all players and can quickly lead to a wipe if not interrupted. Saprish himself places traps all over the floor, which can be difficult see. This fight is turned up to 11 if Necrotic is the level 2 affix, as it can make dropping stacks for the tank extremely difficult.
      • Viceroy Nezhar has a wide variety of dangerous abilities. He periodically summons tentacles that deal high single target damage to random players, attempts to push the group back while shadows expand inwards to the centre from the walls, turning this into a Time-Limit Boss, and attempts to fear all players similarly to Shadewing's Screech. On top of this, the group must save burst dps and at least one interrupt for Eternal Twilight; two adds will place a shield around the Viceroy as he begins to cast a spell that will oneshot the group if not interrupted.
      • The last boss, L'ura, begins the fight by shielding itself and having a single Rift Warden fight the group. These adds spawn Fragments of Despair, which must be stood in by at least one player or the whole group explodes. Killing the Rift Warden gives the group a chance to attack L'ura, who drops the shield and takes increased damage for around 10 seconds. Afterwards, two Rift Wardens spawn and the group must defeat them to progress into phase 2. In phase 2, L'ura becomes active, and the main danger of the fight becomes the ever increasing aoe damage the group constantly takes. With grievous and tyrannical, this phase can be incredibly taxing for healers.
  • The fight against Il'gynoth in the Emerald Nightmare raid is a contest of juggling deadly and complex adds while fighting a boss that requires nearly everyone to be alive. The fight revolves around destroying the bosses eye, which takes no damage from everything except the death explosions of its own Nightmare Ichor adds. These adds are spawned whenever the other adds in the fight are killed and fixate on a random player, leaving that player to possibly avoid Nightmare Corruption on the ground and forcing the Nightmare Ichor's in front of the bosses eye. They aren't the reason the boss is on here. The real reason is the veritable army of aforementioned adds that need to die to spawn them in the first place. Dominator Tentacles need to always be tanked, but aren't that difficult to deal with compared to the other adds. Deathglare Tentacles must be interrupted or someone is most likely gonna die from their very damaging Mind Flay. Corrupter Tentacles must be killed almost as soon as they spawn, lest they start spamming high raid-wide damage like no tomorrow. Finally, the Nightmare Horror must be kited by a tank to a wall or it will start blasting a very damaging eye laser that will almost certainly oneshot anything it hits. Keep in mind the entire time the eye itself is shooting out lasers that take off roughly 1/3rd of an average player's health. Once the Eye is finally dead you have to kill all adds before going in the tree, or they will also do raid wide damage. Finally, you have to avoid Living Bomb style debuffs inside the tree itself while killing the heart and get out before it casts Dark Reconstitution, which kills anyone still inside. You have to kill the eye twice. Thankfully, you're given more time the kill the heart the second time, because the spell it casts then, while killing the entire raid no matter what, takes nearly twice as much time to cast as Dark Reconstitution. The boss is actually not too difficult as an organized group, but good luck beating it without dying multiple times in a PUG.
  • Tichondrius is the brick wall of the Nighthold, being an extremely tight DPS and gear check where a single mistake can easily wipe the raid. He requires the raid to split into two groups to deal with his Carrion Swarm, or else his Carrion Plague will spread to everyone in the group. He also summons a group of blood adds that must be tanked away from him and downed quickly. In phase 2, he throws every single player into an illusion and summons swarms of bats that drop large purple orbs when killed. Beating the enrage timer requires every single DPS in the group to pick up one of the orbs for a damage boost.
  • Star Augur Etraeus is not as hard as some of the other fights in the Nighthold, but has gained a reputation for destroying LFR groups who think they can bum rush the boss thanks to one ability. In the last phase he summons a "Thing That Should Not Be", an add that does stacking raid-wide damage, and puts a 99% damage reduction buff on itself and the boss; one of the tanks needs to pull the add away from the boss to break the shield, and the raid needs burn down the add before going back to the boss. The add also casts a raid-wide fear which hits all players looking at it, so if the tank holding the add doesn't turn away in time, the tank will run around in a panic, likely dragging the add right back into the boss so the shield comes back. And if that wasn't bad enough, the boss summons another Thing That Should Not Be every minute. Because this relies on one person doing the right thing, it's common for a raid to fall to pieces because of the tanks not knowing the fight, or to be saved by a DPS with a Taunt who does.
  • The Maiden of Vigilance in the Tomb of Sargeras is an interesting case. She's drawn a lot of comparisons to the Thaddius fight in Naxxramas. She has very simple mechanics, certainly much less complex than several of the bosses that precede her, but very strictly punishes groups in which even one player fails to follow them. This means that she has acquired a reputation as a bloody-handed, slasher smile-bedecked murderer of PU Gs. More specifically, she marks players with one of two colors. Touching a player or certain mechanics of the opposite color will turn the player into a bomb, taking heavy damage over time and hitting the whole raid when the timer expires. Players can jump into a hole in the center of the room to prevent the raid-wide damage, but if they jump too early they'll fall to their deaths. All of this is pretty easy to deal with, and this fight is more of a damage and healing check than a mechanics test for coordinated groups. But if one player ignores the colors and stands on the wrong side of the room? Congratulations, half your raid is now the bomb. Best case scenario, healers blow their cooldowns, bombs jump at the right time, and only a few people die to damage over time or falls. More likely, though, several people will fail the jump portion of the mechanic and the raid will wipe instantly.
    • Making it even worse is a mechanic where players have to dodge orbs of the 2 colours which move in lanes around the room like guitar hero notes. Though players can easily move between the lanes and entirely avoid the mechanic, collecting orbs that match their colour gives them a damage/healing boost. But as with the rest of the fight, a player grabbing the wrong colour puts a bomb on them. So if one player decides they want to buff their output but lacks the reaction to avoid the wrong orbs, the group suffers.
  • Kil'Jaeden is That One Boss even by final boss standards. In fact, he's arguably that one boss for the entire history of the game to that point, taking the largest number of wipes to defeat on the highest difficulty of any boss for whom the number was reliably tracked. It wasn't close, either: 650 for Method's world first kill (and close to 1000 for many other high level guilds), whereas most legendarily difficult bosses like Yog 0, heroic Ragnaros, mythic Fallen Avatar (who immediately preceded him), and mythic Archimonde took more like 450-500. Nor was this massive difficulty a mythic-only phenomenon: his heroic and normal versions often gave guilds substantially more trouble than the first several bosses of the next difficulty up.
This difficulty was less a matter of having That One Attack and more that nearly every one of his attacks presented a serious threat to the raid. He could rip the tanks apart with felclaws, summon frequent rains of meteors that required most of the raid to soak (and take heavy damage in the process) to avoid wiping, knock poorly-positioned players off the platform to their deaths, summon adds that did devastating raid damage (and turned the whole area into a Bullet Hell on mythic), gradually fill the platform with lethal beam-shooting spires, and much, much more. The darkness phase was mostly cheesed on mythic, but on lower difficulties with less prepared groups it could easily turn into a Goddamned Boss moment as the raid frantically ran around trying to find Illidan and the adds they needed to kill to reveal the main boss.
  • Antorus, The Burning Throne contains quite possibly the most annoying and mechanic-strict boss fight in a while - the Coven of Shivarra. Not only it requires tanks to switch between two bosses every several seconds so they can actually be damaged, the bosses also have several annoying abilities, including some devastating Ao E attacks, a debuff that will freeze you if you don't heal it over and a near-instant death move. The worst part about the fight are the Titans, being forced to use their power against you. Khazgaroth will quickly kill people who don't move away from his flames, Golganeth wipes groups who stand to close to each other, Norgannon can insta-kill anyone who comes near his spectral images and Aman'thul applies an increasing Do T if you don't kill his images fast enough. Groups usually keep their Bloodlust for that particular moment to avoid stacking damage too high, but this fight requires massive amounts of coordination to defeat.
    • It's even worse on Heroic mode, where it becomes sort of a Luck-Based Mission - if the RNG hates you, it can make the Coven use an ability that requires you to be in one spot to avoid dying while ALSO spawning a Titan add that can kill you regardless (such as standing in white circles to avoid Storm of Darkness, but immediately after, the raid dies to Golganneth's Fury).
  • Also from Antorus, there's the sixth boss, Imonar the Soulhunter. His abilities aren't too bad provided that the raid handles them intelligently, but he has two transition phases in which the raid must cross a trap-infested bridge, full of hazards that can severely damage individuals and raids. It gets especially hard on Mythic, when the traps are deadlier, winds are blowing during the bridge phases, and you have to cross the bridge four times.
  • While not as difficult as the Coven, Aggramar can be fairly challenging, especially on Heroic. At 80% and 40% health, he summons six adds that do massive raid-wide damage if they reach him. On Normal, it's a simple matter of killing them before they reach him, but on Heroic and above, they eventually resurrect after being killed, and after reaching him, put a DOT on players. It's very difficult to survive two reaching the boss in rapid succession without use of healing cooldowns, thus forcing you to let them reach him in a highly controlled manner, lest you wipe.
  • The Nighthold. Mythic. Gul'dan. You are not prepared. To start, Gul'dan begins the encounter in his empowered "second phase" form, and it only gets worse from there. His attacks hit harder, more frequently, and the margin for any error becomes razor thin. Twice during the encounter, he uses a wind attack designed to sweep inattentive raiders clear off the platform, out of reach of any resurrection spells. Cooperation between all parties involved is paramount, because if too many raiders die before the hidden phase, failure is all but assured. At a tenth of Gul'dan's remaining health, Archmage Khadgar attempts to return Illidan Stormrage's soul to his currently vacant imprisoned body. It doesn't work. The raid then has a limited amount of time to finish off Gul'dan before The Demon Within becomes active; an unforgiving encounter featuring at least one attack that guarantees a raid wipe 100% of the time should the raid miss the crucial moment necessary to avoid the damage. All this while having to deal with the constant threat of shadow parasites.


     Battle for Azeroth 
  • MOTHER is a strict mechanics fight that heavily relies on team coordination and interrupt skill. The ecounter requires the group to run through three rooms separated by Defense Grids that damage the whole raid when people go through them, requiring the raid to split into groups to slowly shuttle the raid through each one, all while wind threatens to blow players into deadly fire and lasers cut through the room. At the same time adds will spawn that cast Clinging Corruption on the entire raid, doing massive damage in the process, and the adds need to be interrupted by the first group that moves through the grids. If too many people go through the Defense Grids at one time, or if the first group going into each room fails a single Clinging Corruption interrupt, the raid will wipe.
  • After MOTHER comes the Fetid Devourer, which is THE One Boss for tanks on Heroic or higher, being an extremely difficult gear and health check. The boss deals ludicrous physical damage on the tanks and requires them to soak Terrible Thrash every fourth hit, or else the resulting raid-wide debuff will wipe the group. This gets even worse at 50% when he gains Fetid Frenzy and starts hitting much harder than before.
  • Zul, Reborn is probably the most difficult boss in Uldir apart from G'huun. He has multiple types of adds, voidzones and even a dispellable debuff that will cause players to walk toward the edge and throw themselves off.
  • Speaking of the devil, G'huun himself is a brutal fight where the group has to essentially split into three. One has to Hold the Line against increasingly huge number of flunkies. Not to mention that when said flunkies die, they spawn two Chest Burster Spawns that multiply unless they are quickly dealt with, and can easily spiral out of control. Meanwhile, the other two teams have to carry orbs to charge the reactor to actually reveal G'huun and, on Mythic, the two orbs have to be inserted simultaneously. Three times, with characters who carried the orb before being ineligible for it, necessitating the rotation. And this is only the first phase.
  • Greed in the Dazar'alor raid was the biggest stumbling block for raids that tier. At the start of the fight the raid must split into two parts, each of which will fight a mini-boss with its own unique moveset. To complicate matters, the mini-boss is fought in a series of chambers it will move through as the fight goes on, each triggering a different set of traps which must be dealt with on top of the fight. Surviving this sequence with enough players to reach the end is the biggest challenge of the fight, made even harder on Mythic when players will randomly swap sides. The mini-bosses must die at almost the same time to avoid empowering the actual boss. Said boss is fought on a platform subject to Boss Arena Urgency as he will spawn an increasing number of damaging pools as the fight progresses.
  • Ashvane in the Eternal Palace is a hard gear check with a set of mechanics that will quickly overwhelm the players with damage if not handled properly. The boss has a shell which must be destroyed before her actual HP can be damaged. However throughout the fight Ashvane spawns corals which will repair the shell unless the orbs they spawn are intercepted, which causes a burst of raid-wide damage. During the shell break phase, pairs of players will randomly be set to shoot a beam between them and must coordinate in a matter of seconds to ensure this beam breaks as many corals as possible; if too many are left intact, the orb burst damage will overwhelm healers. All of this is on top of her other dangerous abilities: Whirlpools which hurtle players into the air, bubbles which will ensnare anyone near the target, and patches of damaging coral on the floor that is permanent on mythic.
  • Vexiona is harder than she looks that truly requires the raid to watch where they're damaging. Like many other bosses in Ny'alotha, she summons flunkies which have to be taken care of... one of which is a miniboss in itself that will wreck the party. All while she summons a lot of bombs that will cause the area to get covered in damaging-things that the party has to handle. What's more, Vexiona takes flight and will deep breath onto the raid - causing 1/3rd of the area to receive near instant-death. The only way to tell where she'll fire is to literally tilt your camera, something most players aren't used to doing.
  • N'zoth the corrupter is considered to be one of the hardest raid bosses ever - if only a few people don't know what they're doing, even early on, the entire raid can be wiped. He is basically a Final-Exam Boss, combining the sanity of the previous phase (Along with Yogg'saron and even the corrupted Taran Zhu from Mists of Pandaria), requiring the kiting of Deathwing's back, add management of many other bosses, and even watching the direction he'll pull you towards harmful Geo Effects.

  • Sludgefist in Castle Nathria qualifies. While he is, on the surface, a gear check boss on par with Patchwerk, his abilities make the fight quite hard. First, he possesses a "Hateful Strike"-esque ability, inflicting his melee damage on the tank and another target in melee range. Second, he regularily stomps the ground, inflicting enough damage to kill any player in a 20-yard radius around him. After his stomps, debris rains down from above, stunning anyone it lands on and leaving a damaging zone behind. Third, every minute or so, he fixates the tank and charges towards them after four seconds. If this charge doesn't hit one of the four columns in the room, all raid members suffer a debuff that will kill them in seconds. Oh, and the stomps mentioned above can also destroy the columns if it hits them. Lastly, starting on normal difficulty, the boss chains together players for a minute, making them take lethal damage if the chains are broken if the players move too far apart while trying to dodge his other abilities. Even one death early on can mean failing to meet the damage requirement even if everyone is geared adequately.
  • Margrave Stradama in Plaguefall is designed as a healing check boss by virtue of her powerful and steadily-ramping disease damage debuff that she applies at certain points in the fight. This means that your healer will constantly be stressed out to hell trying to heal if you don't have anything to dispel the debuff, and woe be to any brave healer that attempts to do this dungeon on a Grievous week. In addition to that, she has an annoying interval phase in which she spawns near-lethal tentacles around her at random, necessitating you move quickly to avoid getting hit. This is even worse for classes with near-to-no mobility, such as priests and paladins.
  • General Kaal's gauntlet in Sanguine Depths is this by the sheer amount of mobs you have to go through just to get to her. To wit — her fight is designed with two phases: A gauntlet-style chasing phase where you try to burn down Kaal as fast as possible while going through several packs of mobs and a pair of gargons that keep spawning no matter where you are in the gauntlet, and a second phase in which you're fighting Kaal in a small, open ledge overlooking the anima vortex Denathrius created. In all phases of the entire fight, you have to use Zr'ali's Shining Radiance to avoid massive damage in the first phase, and getting blown off the ledge in the second phase, and in the second phase of the fight, you'll be dealing with periodic AoE bleeds that you need to separate yourself from the group from, lest you cause your poor healer to short-circuit from the amount of stacking damage you'll take. All the while, Kaal will occasionally summon three shades of herself cleaving everybody in the way for massive damage unless you dodge them, and since all three shades cover the entire area of the ledge, have fun trying to dance around that AND the AoE bleed while not straying too far from the person holding Zr'ali so that you won't get punted off the ledge.
    • Really, the entire of Sanguine Depths could quality if we speak about the bosses. Kryxis is a pretty crude Tankbuster(High tank damage) and a nightmare to heal when the orb phase starts, as it requires soaking to prevent boss from healing, while each soak done deals a LOT of group damage. Inquisitor can potentially melt a player in seconds on tyrannical weeks with his castigate casts, which targets a random player and deals a high amount of burst damage over several seconds, so much that its advised to bring a hunter purely to abuse feing death to interrupt castigate channel(and thus negate the damage entirely) and spare some mana from healer.
  • De Other Side in terms of bosses, have Hakkar and Dealer Xy'era. Even on non-tyrannical weeks, this bosses are basically the roadblocks of the whole dungeon. Xy'era is a massive healer strain and high-damage boss, to the point he got some hefty nerfs and is still a pretty unforgiving boss in general and a pretty gruelling one whenever grievous affix is active. And lets not start with Hakkar, which is known as the real roadblock/run killer of the dungeon for a very good reason. Hakkar summons snakes and will regulary summon more as the fight goes on, and each time he hits 100 energy, he deals large AOE damage to the whole group and gains a damage absorb that grows bigger if he successfully dealt damage with the 100 energy AOE all while he is busy doing his mechanics and gainin energy to re-do the AOE again. It's a fight that pretty much boils down to "Have a comp with good damage-reduction/absorbs/inmunities, burn Hakkar down and pray you kill him before adds overwhelm you or you take too long. It's entirely possible if you run the wrong comp or you allow a new shield to happen before you broke old one (which can totally happen if your comp lacks the tools to deal with the adds, who detonates and add up to his already large shield if they live when Hakkar hits 100 energy, or don't have a way to keep the shield absorb low by reducing/negating AOE damage) to fail the timer of the dungeon. He is one of the very few dungeon bosses in the whole game to effectively demand a strict comp and punish you if you don't burn him fast enough.
    • Thankfully, Hakkar finally got nerfed to a much more reasonable state in 9.1. Now he stops doing mechanics other than launching easy to dodge missiles when his barrier is up and doesn't gain energy until the barrier is broken, allowing you to catch your breath and preventing the fight from dragging for too long.
  • Anduin Wrynn from Sepulcher of the First Ones is pretty much the hardest boss in the entire raid. His main mechanic is Kingsmourne Hungers, where the raid gets split in half, one half still fighting Anduin, while the other is trasported inside Kingsmourne, where they need to deal with the enemies to strengthen Anduin's willpower, in order to get a damage/damage resistance buff during the intermission. If his willpower is not at least 90%? The raid wipes to sheer damage. He also constantly spams a stacking raid-wide DoT that is only cleared out during intermissions, where it's replaced by a different, stronger, DoT (which puts constant pressure on healers). Among other notable mechanics are Befouled Barrier (creates a zone that absorbs all healing in it until it exhausts, explodes with raid-wiping power if not exhausted), Blasphemy (where each raid member gets marked with one of two marks that explode with enough power to kill whoever they are on upon expiration or if two same marks touch, two opposite marks remove both), Grim Reflections (summons three copies that cast Psychic Terror that fears and DoTs the entire raid if not kicked/crowd controlled/killed, even one such cast succeding is enough for a wipe, and they become practically unkillable if they survive to the intermission), Wicked Star (Projectiles that deal damage and inflict Silence on whoever they hit on the way, before flying back to the boss for a potential second hit) and Hopelessness (like Blasphemy, except there is only one kind of mark that has to be removed by entering a specific area, and that also applies a short duration, stacking DoT upon removal). Even on Normal, the sheer amount of mechanics people have to pay attention to in order to not kill themselves or even the entire raid, combined with the length of the fight (it can easily last over 10 minutes) makes Anduin the one boss that walls just about every group.